Optionally, join the SCP-INT Discord server. Not only is Discord the fastest way to get feedback on a translation you may be working on, but this is a great way to get to know your audience as well as senior staff and other veteran members of the site.

Above all, keep this in mind:

Using the sandbox is not sufficient to ensure that your article will be good.

The whole point of the sandbox is that you will give people a link to your drafts page in order for them to help you. You are strongly encouraged to use the aforementioned resources to get information and feedback before posting your article to the main site — otherwise, your sandbox didn't do you much good.